DE3041358A1 - LIGHT REFLECTIVE OHMSCHER CONTACT FOR COMPONENTS - Google Patents

Description

Light-reflecting ohmic contact for components

The invention "relates to a light reflective ohmic Contact for components, in particular semiconductor components, consisting of a sequence of layers including Gold on a substrate.

For the efficiency of luminescence diodes with transparent substrates, the light reflection is on the back of the substrate is of great importance. There is usually an electrical contact on this back for supplying power to a zone of one conductivity type of the substrate. But this contact is highly light-absorbing if it has the desired electrical properties, namely a low ohmic Resistance, has. To avoid this light absorption, So far, the back of the substrate has therefore only been partially provided with an ohmic contact. Due to the lower However, the electrical properties in particular are impaired on the contact surface, that is, on The transition between the contact and the substrate is a resistance with an often undesirable level. aside from that the smaller contact area reduces the durability of the contact on the substrate.

It is therefore the object of the invention to provide a light-reflecting specify ohmic contact which, with high light reflection, has the desired electrical properties, so should have a low ohmic resistance.

This object is achieved according to the invention in the case of a light-reflecting ohmic contact of the type mentioned at the beginning

Feces 1 Dx / 10/31/1980

VPA 8OP 1 17 in that the layer sequence has a first layer of gold and germanium in a weight ratio of about 99: 1, a second layer of purest silver and a third layer of purest gold.

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Advantageously, the first layer is about 0.02 / µm (200 Å), the second layer 0.8 / µm and the third layer 0.5 µm thick. Such a contact is particularly advantageous for luminescence diodes. He is but can also be used when a substrate is to be contacted with a light-reflecting layer.

Advantageously, this contact is made so that the individual layers on the back of the substrate are vapor-deposited and then sintered there. The ohmic contact produced in this way shows with a low ohmic resistance an excellent light reflection.

The invention is explained in more detail below with reference to the drawing. Show it:

1 shows a light-emitting diode in section, and FIG. 2 shows the sequence of layers of the contact according to the invention.

In FIG. 1, a semiconductor substrate 1 consists of an η-conductive zone 2 and a p-conductive zone 3 »die are separated from each other by a pn junction 4. On the zone 3, a contact 5 is attached, which with a Wire 6 is connected as a lead. From the surface 7 of this zone 3, light is emitted, as is done by Arrows 8 is indicated. The substrate 1 is translucent. In order to achieve a high level of efficiency, the light generated in the substrate 1 and preferably at the pn junction from the back of the substrate 1, respectively of zone 2 are reflected and so about the

ORIGINAL INSPECTED

2041358

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Surface 7 leave the substrate 1. The contact 10 provided on the rear side of the substrate 1 is used for this purpose designed light-reflecting, so that there the light generated inside the substrate 1 is reflected, as indicated by an arrow 11.

According to the invention, this contact 10 consists of a layer sequence (see FIG. 2) with a first, 0.02 / μm thick layer 12 made of gold and germanium in a Ge weight ratio of about 99: 1 $ and a second, 0.8 / μm thick layer 13 made of the purest silver and a third, 0.5 / µm thick layer 14 made of the purest gold. The layer 12 is located on the surface of zone 2.

The individual layers are vapor-deposited one after the other over the entire surface of zone 2. Afterward these layers are sintered. The contact produced in this way has the desired properties of high Light reflection and a low ohmic resistance.

2 figures

4 claims

ORJGiMAL INSPECTED

Claims (4)

^VPA 80 P 1 1 7 8 DE Claims Light-reflecting ohmic contact for components, in particular semiconductor components, consisting of a sequence of layers including gold on a substrate, characterized in that that the layer sequence is a first layer (12) made of gold and germanium in a weight ratio of about 99: 1, a has a second layer (13) made of the purest silver and a third layer (14) made of the purest gold. 2. Contact according to claim 1, characterized in that the first layer (12) about 0.02 / µm (200 ft), the second layer (13) 0.8 / µm and the third layer (14) 0.5 / µm thick. 3. Use of the contact according to claim 1 or 2 for light emitting diodes (1). 4. A method for producing the contact according to claim 1 or 2, characterized in that the individual layers (12, 13, 14) the back of the substrate (1) are vapor-deposited and then sintered on.